The present invention relates to a transceiver comprising transmitter means and receiver means, mode means coupled to the transmitter means and the receiver means for performing a signal transmission/receiving mode of the transceiver, an oscillator means coupled to each of the transmitter means and the receiver means respectively.
Such a transceiver suitable for application in a communication system is known from EP-A-0 752 761. The known transceiver comprises an heterodyne receiver circuit having an antennae, diplex mode means, a transmitter circuit and a receiver circuit, and a local oscillator coupled to each of the transmitter and receiver circuits. The diplex mode means are embodied to allow either a signal transmission mode or a signal receiving mode, while use is being made of one local oscillator in both diplex modes. It is a disadvantage, that the known transceiver is not capable of allowing signals to be simultaneously received and sent.
It is an object of the present invention to provide a transceiver and telecommunication system having such a transceiver, which is capable of operating in full duplex mode without the necessity to adding extra oscillator means to achieve such an operational mode.
To this end in the transceiver according to the invention, the mode means are embodied to allow a simultaneous receiving and transmitting of signals, and the transceiver comprises frequency divider means coupled between the oscillator means on the one hand and the transmitter means, and receiver means respectively on the other hand. It is an advantage of the transceiver according to the invention despite its extended mode capabilities still only one local oscillator means is needed for operation in full duplex mode. This saves components, costs, chip area, power dissipation and weight otherwise spent on added circuitry. This makes the transceiver according to the invention well suitable for communication systems, such as radio transmission systems, audio- and/or video systems, control systems, telemetry systems, local area networks, wide area networks, and very well suitable for application in cordless or cellular telephone systems, as well as in handset, a car-transceiver for mobile communication, or a transceiver in a radio base station of a mobile network.
An embodiment of the transceiver according to the invention, which is very easy to integrate on only a limited chip area has the characterising features that the frequency divider means comprises at least one divider, preferably at least one 2-divider.
A further embodiment of the transceiver according to the invention is characterised in that the transceiver comprises short-circuiting means bypassing at least one of the dividers. The advantage thereof is that bypassing one or more of the dividers provides the possibility of frequency band switching, therewith switching from one working frequency used in the telecommunication system such as 900 MHz to another such as 1900 MHz.